Internal-combustion engine



S. I. PRESCOTT INTERNAL COMBUSTIONENGINE Filed Feb. 19. 1921' gaa if .i..i Ii

Patented Feb. 24, 1925.

mm 1'. PRESCOTT, 0] NEW YORK, N.

ra'rnanan-counusrron meme.

Application filed February 10, 1921. Serial Io. 446,246.

To all whom it may camera:

Be it known that I, SYDNEY I. Plmsoo'rr, a citizen of the United States, residing at New York, county of New York, and'state of New York, have invented a new and useful Improvement in Internal-Combustion Engines, of which the following is a specification.

This invention relates to an improvement in internal combustion engines of the rotary valve type.

The cylinders and valve housings of such engines are customarily constructed of cast iron or semi-steel which has a fixed co-eflicient' of expansion. A rotary valve 'must be close fit in its housing in order to insure proper suction and gas compression, or the engme cannot develop the power for which it is designed; and it must not bind in its housing for that will destro its utility. If a rotary valve is constructe of cast iron, and is a close fit in its housing when cold, it will insure proper suction and s compression as the engine is started, ut Wlll invariably bind in its housing when it is expanded, by hot exhaust gas contacting with it, to a greater extent than the housing is expanded. Numerous attempts have been made to overcome this difliculty by the use of some sort of cooling system for the valve, but such designs import new complications and difliculties of their own and have not proven efiicient for the designed purpose, mainly because it was found impossible by their use to maintain equal valve and housing temperatures since the valve and its housing are subjected to widely differin degrees of heat. And if the valve is a oose fit in its housing when cold, so

that when hot it will not bind therein, it is invariably inefiicient for the essential suction and compresion purposes, and therefore uneconomical and unsatisfactory. When a rotary valve was constructed of other metal, as some have been, the efiect was worse. It has been discovered that the heretofore existing lack of control of the difierential explanslon of a rotary valve and its housin "w on subjected to the widely differing egrees of heat encountered in practical operation of internal combustion engines, is the underlying cause of the commercial' failure of rota valve engines heretofore built. And it has further been discovered that-the difliculty can be overcome by constructing a rotary valve of an alloy havin a compensating coeflicient of expansion etermined in accordance with the working or actual expansion of the valve housing; or, in other words, by a rotary valve constructed of an alloy the composition of which depends upon the differential rates of expansion of a housing and its valve under working or actual temperatures, the latter being determined by the former and so justified with respect thereto as to insure the maintenance of a close working fit of the valve in its housing throughout the ,range of working temperatures to which the parts are subjected. The production of such a compensated valve is one of the objects of the invention. Another difliculty heretofore encountered was the lack of eflicient lubrication. The variations in the clearance of the valve in its housing, due to their unequal expansion, operated against the proper retention of a film of oil between their surfaces, and the high heat of the exhaust gas contacting with and heating the valve operated to burn the oil unevenly, often before it could perform its lubricating function. It has been discovered that with a com nsated rotary valve maintaining a practically constant working fit with its housing, this difiiculty can be overcome by incorporating with the valve and housing organization and adequate self-contained lubricating means of the graphite type which successfully resists the heat and in ricates without interfering with the differential expansion of the parts. The production of such an organization is another object of the invention. With these and other objects not specifically mentioned in view, the invention consists in certain con- 'structions and combinations which will be hereinafter fully described and then specifically set forth in the claims hereunto appended.

The accompanying drawing, which forms a part of this specification, is a cross-sectional view of the upper part of the cylinder of a four-stroke-cycle engine and its cylinder head, constructed in accordance with the invention.

In carrying the invention into eflect, there is provided a communicating cylinder and valve housing, or a series of cylinders and a valve housing common to all cylinders, and a rotary valve working in said housing and constructed of an alloy having a compensating coefiicient of expansion determined in accordance with the working expansion of the housing, whereby a highly efficient working fit of the parts is maintained at all working temperatures. In the best constructions, there is also provided self-contained lubricating means for the valve, and.the housing is integral with the cylinder head and surmounts its combustion chamber.

Referring to the drawing, 1 indicates a vertical cylinder provided with a water jacket 2 of well known type. The upper end of the cylinder is closed by a cylinder head 3 provided with a similar water jacket 4. The cylinder head is provided with a combustion chamber 5 of hemispherical form for high efiioiency, and with the usual' haust pipes or manifolds, not shown but of' well known construction. The valve housing is further provided, oppos te said intake and exhaust ports 9 and 10, with rectangular chamber ports 11 and'12leading from the interior of the housing tosaid chamber. As shown, the ports 9, 10, 11 and 12 extend through the lubricating bush 8, and it is to be understood that their relative circumferential positions and their amplitude depends upon the valve timing of the engine in which they are used.

Driven by suitable mechanism of well known character and not shown, and working in the valve housing 7, within the lubricating bush 8, is a compensated rotary valve 13 having a rectangular through port 14 controlling the opening and closing of the ports before referred to and thereby controlling infiuxion to and efifluxion from said combustion chamber. This valve rotates in the direction indicated by the arrow in the drawing.

When the parts are in the position shown in the drawing, the engine piston, not shown, will be a little beyond the upper dead ccntcr at the beginning of the induction stroke. At this time, the valve 13 has just closed the chamber port 12 and the exhaust port 10 and is at its highest temperature and about to open the intake port 9 to the ber port 11 by means of the valve port 14. As the piston moves down on the induction stroke, fresh gas is drawn through thQrllOt valve and, by absorbing some of' itsljheat,

increases its own eificiency and prevents overheating of the valve. hen the piston has passed lower dead center and reached the chamber ports 11 and 12 against the lower side of the valve in the wake of said ports, tends to press its upper side against the up er half of the housing and eifectually close the intake and exhaust ports 9 and 10, and thereby prevent escape of gas and loss of pressure by valve leakage, even in the event of a badly worn valve. The combined cross-sectional area of the chamber ports 11 and 12, however, is small as compared with the bearing area of the valve as a whole, and, in consequence, the pressure of the valve against the housing does not interfere with its free and smooth operation, nor produce excessive wear. When the compressed charge of gas is ignited, near the end- 1 of the compression stroke, the valve port 14 open communication continues until just before the valve reaches the position shown in j the drawing. Thereafter, the cycle of operation is repeated.

The cylinder, valve housing, and bush, are

constructed of cast iron or semi-steel, the bush being plugged with graphite in a well knownmanner; and these parts therefore have thesame coeflicient of expansion, and since the water cooling system is designed to maintain the temperature of the castings at about 170 F., the working or actual expansion, or enlargement by heat, of the housi'ng-and bush is definite in extent. The hot exhaust gas passes through the valve and the working temperature of said valve is thereforeconsiderably higher than the temperature of the valve housing and bush in which it works. To compensate for 'the diiferential working temperatures, and thus provide for a very close working fit of the valve and bush throughout the range ofworking temperatures between'a cold and a hot engine, the valve is constructed of an alloy having a compensating coeificient of expansion de termined in accordance with the working expansion of the valve housing and bush. As-

suming that in the engine illustrated the valve housing bush is 2.500" in diameter, and'the diameter of the compensated valve is 2.499 f when cold: I When the valve housing and bush are expanded by heat to their working temperaturegthje diameter of the bush is 2.502.2"ff To have the valve, in the engine illustrated, is made of an alloy composed of approximately 70% of iron and 30% of nickel. The coefiicient of expansion of this particular alloy is lower than that of cast iron'or semi-steel; or, in other words, its rate of expansion is slower.

" But in view of the higher temperature of the valve, its slower rate of expansion just compensates for the lower temperature but faster rate of expansion of the valve housing and bush, at working temperatures. It

7 may be here remarked that although the designed difference in diameter of the valve and bush is .001", which of course ro-vides a clearance-all around of .0005, the 1s not the actual clearance, because the surface of the valve quickly becomes covered with a film of graphite which reduces this clearance, lubricates and makes the valve gas-tight, and is indestructible. By this construction, an extremely close fit is made and maintained throughout the range of temperatures differential workin expansions of the valve encountered in the practical operation of the engine.

When, however, an engine is designed to have a valve of a different diameter, the

and its housing wil be greater or less as the case may be, and in that event a slightly different alloy will be necessary, because the coefiicient of expansion of this kind of alloy changes very rapidly when its component parts vary from the given proportion, and the alloy must always be determined in ac cordance with the working oractual expansion of the valve housing, and the proportions of the metals in the alloy must be determined in accordance with an inherent coeflicient of expansion which will compensate for the change expansion conditions existing in the new valve housing.

The structure selected to illustrate the invention is but one of many possible concrete embodiments ofthe. same, and changes and variations within the scope of the'claims ma be made in the structure by means of which the invention is carried into effect. The invention, therefore, is not to be restricted to the precise detailsof the structure shown and described.

. What is claimed is:

1. In an internal combustion engine, the combination witha cylinder head provided with a combustion chamber, of a cylindrical valve housing having intake and exhaust and chamber ports, and a compensated rotary valve working in said housing and controlling influxion to and efiluxion from said chamber, said valve being constructed of an alloy having a compensating coeflicient of expansion determined in accordhousing.

2. In an internal combustion engine, the combination with a cylinder head provided with a combustion chamber, of a cylindrical valve housing having intake and exhaust ports and chamber ports opposite said intake and exhaust ports, and a compensated rotary valve working in said housing and having a through port controlling influxion to and efiiuxion from said chamber, .said valve being constructed of an alloy having a compensating co-elficient oi expansion determined in accordance with the working expansion of said housing.

3. In an internal combustion engine, the combination with a cylinder head provided with a combustion chamber, of a cylindrical valve housing surmount-ing said chamber and having intake and exhaust and chamber ports, and a compensated rotary valve working in said housing and controlling influxion and elfiuxion from said chamber, said valve being constructed of an alloy having a compensating co-eflicient of expansion determined in accordance with the working expansion of said housing. 1

4. In an internal combustion engine, the

ance with the working expansion of said combination with a communicating cylinder and valve housing constructed of cast iron,

of a rotary valve Working in said housing and constructed of an alloy composed of approximately 70% of iron and 30% of nickel.

6. In an internal combustion engine, the combination with a cylinder, of intake and exhaust devices, a valve housing having port connection with said cylinder and devices, and .a compensated rotary valve working in said housing and having a through port swept by eflluxion of hot gas and immediately afterward by influxion of cool gas, said valve being constructed of an alloy having a compensatlng co-efiicient of expansion determined in accordance with the working expansion of said housing.

7. An internal combustion engine rotary valve constructed of an alloy having a compensating eo-eflicient of expansion determined in accordancewith the working expansion of the valve chamber of said engine.

In testimony whereof, I have signed my name to this specification.

SYDNEY I. PRESCOTT.- 

